KNS PRECISION, INC. - AR-15 Perma Pin Firing Pin Retainer

Like that I don't have to fight with the cotter pin to go back in. Will have to see how long it lasts

This makes replacing the firing pin retainer easy.

I used this Retainer on 6.5, 5.56, and .308 BCGs. Much easier to use than the cotter pin

I was looking for something that replaces the standard cotter pin firing pin retaining pin because the cotter pin looks like it will wear out fairly quickly and, oh, yes, the Perma Pin is just the thing, the perfect thing, the long-lasting solution! Maybe that's why they call it the Perma Pin. It should last for a very long time. The Perma Pin is not the easiest thing to get in the hole. You have to play with it for a while to get it inserted in its proper location. KNS recommends working the Perma Pin in and out a few times just by itself with all of the other bolt carrier group parts removed, then assemble the bolt with all of the parts and insert the Perma Pin. On a scale of one to five, Perma Pin is probably a ten-star product. Yes, I recommend it. I think it is the best.

Did not fit my bolt carrier, as my opening for the firing pin retaining pin is more U-shaped, as opposed to the traditional round opening (see pic). This caused the lip of the Perma Pin head to catch on the edge of the opening before it could be fully seated. Tried it on a second bolt carrier, and it did not want to go through the far side. We could probably file it down a bit to make it work, but did not do that yet. Throwing it in the spare parts box for now, as it isn't worth the hassle of sending it back for $10. Great idea, and apparently similar to the original Stoner design, but did not work for me.